Thor supports a number of coding tools that have the potential to improve perceptual as well as objective quality.
Synthetic reference frames may be used to support high frame rate applications in circumstances where encoders might
typically transmit reduced frame rate content. Quantization matrices can be used to give improved visual quality by
allocating bits more closely according to perceptual significance. Thor’s Constrained Low Pass Loop Filter provides
significant subjective benefit in removing coding artefacts such as ringing. Improved colour fidelity can also be obtained
by leveraging luma information. This paper discusses developments in these tools and their objective and subjective
performance.